Elements of theoretical and descriptive astronomy, for the use of colleges and academies (1901)
White, Charles J · New York: J. Wiley & sons · leaf 48
declination axis. 39. Use of the Equatorial.—The equatorial is employed prin-cipally in that class of observatious which requires a celestialbody to remain in the field of view during a considerable lengthof time. The manner in which this requirement is met is explainedin Fig. 13. Let A A be the… … rection of the star when at s, and Fig. 13. to be moved until the intersection of the cross-wires and the staicoincide, and then clamped. Now, if the instrument is made torevolve about the axis AAt with an angular velocity equal tothat of the star about the pole, it is plain that, since the…
Astronomy
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-201-122.webp)
